title: Effect of tinnitus on distortion product otoacoustic emissions varies with hearing loss.
abstract: OBJECTIVE
  The aim of this study was to measure the effect of tinnitus, while accounting for the effect of hearing loss and aging, on distortion product otoacoustic emissions (DPOAEs).
  
  
  METHODS
  DPOAEs were measured twice in both ears in 5 groups of participants: young adults with normal hearing, middle-age adults with normal hearing, adults with high-frequency sensorineural hearing loss, age-matched adults with similar hearing loss and tinnitus, and adults with normal hearing and chronic tinnitus.
  
  
  RESULTS
  Multivariate analysis revealed a main effect of hearing loss and age, but no effect of tinnitus, across all 5 groups. Separate tests revealed significant effects of age and tinnitus in the normal-hearing groups and hearing loss in adults with or without tinnitus, but no effect of tinnitus in those with hearing loss.
  
  
  CONCLUSIONS
  DPOAE levels in the group of adults with hearing loss and tinnitus were diminished, but those in the group with normal hearing and tinnitus were enhanced, relative to DPOAE levels in the controls. Outer hair cell function, as indexed by DPOAEs, exhibits a complex association with tinnitus, and this has implications in the use of DPOAEs as a tool both for testing for tinnitus presence and for creating a model of neural mechanisms underlying tinnitus.
authors.affiliation: University of Illinois at Urbana-Champaign, USA. husainf@illinois.edu
authors.forename: Fatima T
authors.initials: FT
authors.lastname: Husain
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001301:Audiometry, Pure-Tone; D005260:Female; D034381:Hearing Loss / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D014012:Tinnitus / Q000503:physiopathology*; D055815:Young Adult
keywords: DP gram; age; distortion product otoacoustic emissions; hearing loss; outer hair cell; tinnitus